// Copyright 2025 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package fileicon

import (
	"html/template"
	"strings"
	"sync"

	"code.gitea.io/gitea/modules/json"
	"code.gitea.io/gitea/modules/log"
	"code.gitea.io/gitea/modules/options"
	"code.gitea.io/gitea/modules/setting"
	"code.gitea.io/gitea/modules/svg"
	"code.gitea.io/gitea/modules/util"
)

type materialIconRulesData struct {
	FileNames      map[string]string `json:"fileNames"`
	FolderNames    map[string]string `json:"folderNames"`
	FileExtensions map[string]string `json:"fileExtensions"`
	LanguageIDs    map[string]string `json:"languageIds"`
}

type MaterialIconProvider struct {
	once  sync.Once
	rules *materialIconRulesData
	svgs  map[string]string
}

var materialIconProvider MaterialIconProvider

func DefaultMaterialIconProvider() *MaterialIconProvider {
	materialIconProvider.once.Do(materialIconProvider.loadData)
	return &materialIconProvider
}

func (m *MaterialIconProvider) loadData() {
	buf, err := options.AssetFS().ReadFile("fileicon/material-icon-rules.json")
	if err != nil {
		log.Error("Failed to read material icon rules: %v", err)
		return
	}
	err = json.Unmarshal(buf, &m.rules)
	if err != nil {
		log.Error("Failed to unmarshal material icon rules: %v", err)
		return
	}

	buf, err = options.AssetFS().ReadFile("fileicon/material-icon-svgs.json")
	if err != nil {
		log.Error("Failed to read material icon rules: %v", err)
		return
	}
	err = json.Unmarshal(buf, &m.svgs)
	if err != nil {
		log.Error("Failed to unmarshal material icon rules: %v", err)
		return
	}
	log.Debug("Loaded material icon rules and SVG images")
}

func (m *MaterialIconProvider) renderFileIconSVG(p *RenderedIconPool, name, svg, extraClass string) template.HTML {
	// This part is a bit hacky, but it works really well. It should be safe to do so because all SVG icons are generated by us.
	// Will try to refactor this in the future.
	if !strings.HasPrefix(svg, "<svg") {
		panic("Invalid SVG icon")
	}
	svgID := "svg-mfi-" + name
	svgCommonAttrs := `class="svg git-entry-icon ` + extraClass + `" width="16" height="16" aria-hidden="true"`
	svgHTML := template.HTML(`<svg id="` + svgID + `" ` + svgCommonAttrs + svg[4:])
	if p == nil {
		return svgHTML
	}
	if p.IconSVGs[svgID] == "" {
		p.IconSVGs[svgID] = svgHTML
	}
	return template.HTML(`<svg ` + svgCommonAttrs + `><use xlink:href="#` + svgID + `"></use></svg>`)
}

func (m *MaterialIconProvider) EntryIconHTML(p *RenderedIconPool, entry *EntryInfo) template.HTML {
	if m.rules == nil {
		return BasicEntryIconHTML(entry)
	}

	if entry.EntryMode.IsLink() {
		if entry.SymlinkToMode.IsDir() {
			// keep the old "octicon-xxx" class name to make some "theme plugin selector" could still work
			return svg.RenderHTML("material-folder-symlink", 16, "octicon-file-directory-symlink")
		}
		return svg.RenderHTML("octicon-file-symlink-file") // TODO: find some better icons for them
	}

	name := m.FindIconName(entry)
	iconSVG := m.svgs[name]
	if iconSVG == "" {
		name = "file"
		if entry.EntryMode.IsDir() {
			name = util.Iif(entry.IsOpen, "folder-open", "folder")
		}
		iconSVG = m.svgs[name]
		if iconSVG == "" {
			setting.PanicInDevOrTesting("missing file icon for %s", name)
		}
	}

	// keep the old "octicon-xxx" class name to make some "theme plugin selector" could still work
	extraClass := "octicon-file"
	switch {
	case entry.EntryMode.IsDir():
		extraClass = BasicEntryIconName(entry)
	case entry.EntryMode.IsSubModule():
		extraClass = "octicon-file-submodule"
	}
	return m.renderFileIconSVG(p, name, iconSVG, extraClass)
}

func (m *MaterialIconProvider) findIconNameWithLangID(s string) string {
	if _, ok := m.svgs[s]; ok {
		return s
	}
	if s, ok := m.rules.LanguageIDs[s]; ok {
		if _, ok = m.svgs[s]; ok {
			return s
		}
	}
	return ""
}

func (m *MaterialIconProvider) FindIconName(entry *EntryInfo) string {
	if entry.EntryMode.IsSubModule() {
		return "folder-git"
	}

	fileNameLower := strings.ToLower(entry.BaseName)
	if entry.EntryMode.IsDir() {
		if s, ok := m.rules.FolderNames[fileNameLower]; ok {
			return s
		}
		return util.Iif(entry.IsOpen, "folder-open", "folder")
	}

	if s, ok := m.rules.FileNames[fileNameLower]; ok {
		if s = m.findIconNameWithLangID(s); s != "" {
			return s
		}
	}

	for i := len(fileNameLower) - 1; i >= 0; i-- {
		if fileNameLower[i] == '.' {
			ext := fileNameLower[i+1:]
			if s, ok := m.rules.FileExtensions[ext]; ok {
				if s = m.findIconNameWithLangID(s); s != "" {
					return s
				}
			}
		}
	}

	return "file"
}
